Band-Division vs. Space-Division Multiplexing: A Network Performance Statistical Assessment

We compare the networking merit of two possible multiplexing techniques on top of wavelength division multiplexing to enlarge transmission capacity: the band division multiplexing (BDM) that aims at using up to all the U-to-O low-loss transmission bands available on the G-652.D fiber and the spatial division multiplexing (SDM) implemented by activating additional fibers, used on the C-band only. We use the statistical network assessmemnt process (SNAP) to derive the networking performance as blocking probability vs. the total allocated traffic normalized with respect to the multiplexing cardinality. We analyze two network topologies: the German regional network and the US-NET continental network. In case dark fibers are available, SDM upgrades are always the best solution, enabling up to 12% and 17% of extra traffic at blocking probability equal to 10^{-3} on top of the multiplication by the multiplexing cardinality (N_{ ext{M}}) of 12, for the German and US-NET topology, respectively. BDM solutions present worse performance, but mixed BDM/SDM solutions display quite limited penalties with respect to the pure SDM solution, up to the use of 16 THz per fiber. So, mixed BDM/SDM implementation seems the most convenient solution in case of limited availability of dark fibers. Pure BDM solutions occupying a bandwidth larger than 16 THz display an increasingly and considerable gap in the allocated traffic with respect to the pure BDM, therefore, their use must be considered only in case of total absence of available dark fibers.